If you’re a smoker, the best thing you can do for your body—and your lungs, specifically—is quit. But quitting is often a process that can take some time, and in the meantime, you should definitely make sure you keep your vitamin D levels up. Why? A recent study shows that the lung function of a smoker with vitamin D deficiency deteriorates faster than that of a smoker with normal levels of the vitamin, reports HealthDay.com in an article reposted on the US National Institutes of Health website.

To arrive at these findings, researchers studied information from over 600 white male participants in a study on aging who happened to be smokers, comparing data from over 20 years of follow-up. While they did find that there was a more significant decline in lung function in smokers with low levels of vitamin D, they also noted that the effect was small and that taking the vitamin doesn’t significantly affect lung function when comparing smokers to nonsmokers.

But this is not to say that you can continue smoking as long as you keep your vitamin D levels up. The researchers, whose study was published in the American Journal of Respiratory and Critical Care Medicine, warned that taking vitamin D doesn’t actually prevent the deterioration of your lung function, nor does it protect you from other health problems related to smoking, like heart disease, stroke, and cancer. In short, vitamin D doesn’t protect your lungs, but the lack of it just makes things worse.

Lead researcher Nancy E. Langue, MD, MPE, from the Channing Laboratory at the Brigham and Women’s Hospital in Boston, Massachusetts, stresses, “the most important intervention, for both lung and overall health, is for people to stop smoking.”